reedom Plaza is a map.

Located at the corner of Pennsylvania Avenue and Thirteenth Street, the plaza’s vast surface of inlaid stone depicts the streets of Washington as they were originally envisioned by Pierre L’Enfant. The plaza is a popular tourist destination not only because the giant map is fun to walk on, but also because Martin Luther King Jr., for whom Freedom Plaza is named, wrote much of his “I Have a Dream” speech in the nearby Willard Hotel.

D.C. cabdriver Omar Amirana brought tourists to Freedom Plaza all the time, but tonight, his two passengers were obviously no ordinary sightseers. The CIA is chasing them? Omar had barely come to a stop at the curb before the man and woman had jumped out.

“Stay right here!” the man in the tweed coat told Omar. “We’ll be right back!”

Omar watched the two people dash out onto the wide-open spaces of the enormous map, pointing and shouting as they scanned the geometry of intersecting streets. Omar grabbed his cell phone off the dashboard. “Sir, are you still there?”

“Yes, Omar!” a voice shouted, barely audible over a thundering noise on his end of the line. “Where are they now?”

“Out on the map. It seems like they’re looking for something.”

“Do not let them out of your sight,” the agent shouted. “I’m almost there!”

Omar watched as the two fugitives quickly found the plaza’s famous Great Seal—one of the largest bronze medallions ever cast. They stood over it a moment and quickly began pointing to the southwest. Then the man in tweed came racing back toward the cab. Omar quickly set his phone down on the dashboard as the man arrived, breathless.

“Which direction is Alexandria, Virginia?” he demanded.

“Alexandria?” Omar pointed southwest, the exact same direction the man and woman had just pointed toward.

“I knew it!” the man whispered beneath his breath. He spun and shouted back to the woman. “You’re right! Alexandria!”

The woman now pointed across the plaza to an illuminated “Metro” sign nearby. “The Blue Line goes directly there. We want King Street Station!”

Omar felt a surge of panic. Oh no.

The man turned back to Omar and handed him entirely too many bills for the fare. “Thanks. We’re all set.” He hoisted his leather bag and ran off.

“Wait! I can drive you! I go there all the time!”

But it was too late. The man and woman were already dashing across the plaza. They disappeared down the stairs into the Metro Center subway station.

Omar grabbed his cell phone. “Sir! They ran down into the subway! I couldn’t stop them! They’re taking the Blue Line to Alexandria!”

“Stay right there!” the agent shouted. “I’ll be there in fifteen seconds!”

Omar looked down at the wad of bills the man had given him. The bill on top was apparently the one they had been writing on. It had a Jewish star on top of the Great Seal of the United States. Sure enough, the star’s points fell on letters that spelled MASON.

Without warning, Omar felt a deafening vibration all around him, as if a tractor trailer were about to collide with his cab. He looked up, but the street was deserted. The noise increased, and suddenly a sleek black helicopter dropped down out of the night and landed hard in the middle of the plaza map.

A group of black-clad men jumped out. Most ran toward the subway station, but one came dashing toward Omar’s cab. He yanked open the passenger door. “Omar? Is that you?”

Omar nodded, speechless.

“Did they say where they were headed?” the agent demanded.

“Alexandria! King Street Station,” Omar blurted. “I offered to drive, but—”

“Did they say where in Alexandria they were going?”

“No! They looked at the medallion of the Great Seal on the plaza, then they asked about Alexandria, and they paid me with this.” He handed the agent the dollar bill with the bizarre diagram. As the agent studied the bill, Omar suddenly put it all together. The Masons! Alexandria! One of the most famous Masonic buildings in America was in Alexandria. “That’s it!” he blurted. “The George Washington Masonic Memorial! It’s directly across from King Street Station!”

“That it is,” the agent said, apparently having just come to the same realization as the rest of the agents came sprinting back from the station.

“We missed them!” one of the men yelled. “Blue Line just left! They’re not down there!”

Agent Simkins checked his watch and turned back to Omar. “How long does the subway take to Alexandria?”

“Ten minutes at least. Probably more.”

“Omar, you’ve done an excellent job. Thank you.”

“Sure. What’s this all about?!”

But Agent Simkins was already running back to the chopper, shouting as he went. “King Street Station! We’ll get there before they do!”

Bewildered, Omar watched the great black bird lift off. It banked hard to the south across Pennsylvania Avenue, and then thundered off into the night.

Underneath the cabbie’s feet, a subway train was picking up speed as it headed away from Freedom Plaza. On board, Robert Langdon and Katherine Solomon sat breathless, neither one saying a word as the train whisked them toward their destination.